Generator.



B. W. DAVID.

GENERATOR.

APPLiCATlON FILED MAR. 20. l9I5- Snow/viva Patented Feb. 2

@Hotucq UNITED STATES PATENT OFFICE.

BRUCE W. DAVID, OF CLEVELAND, OHIO. ASSIGNOR TO THE LINCOLN ELECTRIC COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

GENERATOR.

Specification of Letters Patent.

Patented Feb. 25, 1919.

Application filed March 20. 1915. Serial No. 15,842.

This invention has utility when incorporated in connection with dynamo electric machines, especially electric generators for handling variable current demands economieally, as the takingc'are of a plurality of arcs automatically independent of the interposition of non-working'or merely load. ing resistance in the circuit.

Figure 1 is a wiring diagram of an em-' bodimentof theinvention, the showing being of an electric generator to supply currenit for a plurality of arcs, say for welding; an

Fig. 2 is a wiring diagram, also of an electric generator for arcs, say for moving picture or pidture projection purposes.

The generator 1 or dynamo electricmachine is provided with the independently excited field winding 2 supplied by the exciter generator 3 having the shunt winding 4; with the rheostat 5 therein adjustable to vary the exciter current and thus control the strength ing 6 with a separately excited field wind-- of the field 2.

Supplementing this separately excited field winding 2, is the shunt field winding 6, which may be adjustable through the rheostat 7 to vary its action as to the current generated by the generator 1.

In addition to these two independent or different circuit field windings 2, 6, there is the third, still different and independent circuit field winding 8. This field winding 8 is in series with the main circuit of the generator 1. In the main circuit 9 from the generator 1 may be the reversing switch 10 to reverse the series field winding 8, say from supplementin the field windings 2, 6, to differential re ation thereto.

Also in series in the main circuit 9 is the reactance 11, tending todampen any sudden fluctuation in current demand and retard res onsiveness thereto at the generator.

s a working load for the main circuit there may be theelectrode 12 adjustable to form an arc with the work 13 in completing circuit to the generator 1 through the line 14 when the switch 15 is open.- A second arc 1s shown from the line 16. This second arc has the electrode 17 adjustable as to the work 18 to draw an are for circuit through the line ll when the switch 15 is open. This structure has utility in picture proectlon, say in changing from one reel to another or from still to moving pictures, the normal running being with a single are. This apparatus without the use of load reslstance, will readily care for the two arcs in its regular generation, thus economically and automatically res onding to this extreme condition. This end is attained through the generator and its plurality of field windings. The multiple field windings introduce independent features of adjustment and automatic control.

Considering the shunt field winding 6 as in operation developin an ascending curve for the field poles laid out on voltage ordinates and ampere turns abscissae, this curve has a general ascending line as to these potential and current elements up to a bend or knee, where approaching saturation of the poles shows the increase in ampere turns giving proportionately less rate of increase of generated volts. By imposing upon, or rather supplementing the shunt field winding, the no load generated volts may .be

moved up along the knee. In addition to the shunt and separately excited windings 6, 2, opposing or counteractin ampere turns may be introduced by the ucking or diiferential' field winding 8. The winding. 6 is designed to have its resistance approximate in direction the straight line below the knee portion of the magnetization curve.

In Fig. 2 there is shown the compressible carbon pile 19 in shunt with the field winding 8, and this adjustment may be operable to vary the action of thegenerator, as well as the rheostats in the contr'ol of the other windings, or inlieu of the direct adjustment of this series field 8 disclosed in Fig. 1.

The arcs in Fig. 2 are shown in series. With the switch 20 open, current may flow through the are 21 which may be drawn to the proper position, while with the switch 22 open, the are 23 in series with the are 2; may be drawn to position.

lnpractice, say for the conditions adranced herein, it has been found desirable-to parallel with the straight ascendin portion of the shunt field winding 6 curve elow the knee thereof. Owing to these factors varying in the generator operation, the shunt curve of generated volts and ampere turns is followed with the no load point farther up along the knee of the curve. When load is applied, as one or two arcs, the voltage drops vbut the fields interact to keep current flow constant.

What is claimed and it is desired to secure by Letters Patent is:

1. A circuit subject to wide changes in resistance, a reactance. to retard current changes, and a generator for said circuit embodying a field ma et, self and separately excited shunt win ings for the generator, said self excited shunt winding atall times being maintained as a self-excited shunt,

the volt ampere turn characteristic of the self-excited shunt winding corresponding to the magnetization curve of the magnet.

2. A circuit sub ect to w1de changes in resistance, a reactance to retard current changes, and a generator for said circuit embodying a field magnet, a series field winding for the generator and self and separately excited shunt windings for the generator, said self-excited shunt winding at all times being maintained as a self-excited shunt, the volt ampere turn characteristic of theself-ercited shunt winding correspond- 

